The catalyst for EY's move was a discussion O'Connor had with Equal Employment Opportunities Commissioner Jackie Blue, who told him businesses were lagging in supporting domestic violence initiatives.
"Really, off the back of that meeting, I just thought it's one of these things that large businesses needed to take a leadership position on and be prepared to break some taboos and talk about it," he says.
Christie Hall, EY's employment and health & safety law leader, says statistics on domestic violence caught the firm by surprise.
In 2014, the police recorded a family violence investigation every five-and-a-half minutes on average.
That year, 101,981 family violence investigations were recorded by police, up 7 per cent from 2013.
But 76 per cent of family violence incidents are not reported to police.
"That then leads to thinking, statistically speaking, there are probably some of our people who are being affected by this," says Hall.
EY employs more than 1000 staff around the country and the new policy, which includes a programme to raise awareness of domestic violence, sits alongside the firm's diversity and inclusion and health and safety policies.
Recent changes in New Zealand's health and safety legislation, and a focus by government regulators on issues such as workplace bullying, have encouraged employers to take a more holistic view of employee health, moving beyond a compliance approach towards nurturing and growing workers' wellbeing.
Healthy workplace initiatives are becoming commonplace but domestic violence has remained a taboo subject, Hall says.
The firm struggled to find local or overseas models for the policy, which has also been rolled out at EY Australia. "I don't think we'd go so far as to say we're the only ones at the moment, but we definitely haven't seen this sort of policy being widely used.
the reality is it's not a blue- or a white-collar problem, it's an everyone problem.
"I think for what is a fairly small spend in terms of resources, hopefully the impact of it will far outweigh that."
O'Connor says he has been stunned by positive feedback from staff. "I had a couple that said that this is why they work for us and that they are proud to work for an organisation that would be prepared to have a policy like this, because the reality is it's not a blue- or a white-collar problem, it's an everyone problem."
O'Connor has talked to several other chief executives about EY's policy and says he hopes it will be picked up more widely. "I don't think there are any downsides to going out and supporting people and talking about it," he says.